From the Wikipedia:
"Pasture commons are those where the primary right is to pasture livestock. In the uplands, they are largely moorland, on the coast they may be salt marsh, sand dunes or cliffs, and on inland lowlands they may be downland, grassland, heathland or wood pasture, depending on the soil and history.
These habitats are often of very high nature conservation value, because of their very long continuity of management—in some cases for many hundreds of years.
In the past, most pasture commons would have been grazed by mixtures of cattle, sheep and ponies (often also geese). The modern survival of grazing on pasture commons over the past century is uneven." (http://en.wikipedia.org/wiki/Common_land)
- Report: Crisis of the Pastoral Commons